Seat apparatus and method

ABSTRACT

A seat apparatus comprises a housing defining at least a first flow path and at least a second flow path, a first seat disposed in the housing for receipt of a first object operative to obstruct the first flow path, and a second seat disposed in the housing for receipt of a second object operative to obstruct the second flow path and method.

BACKGROUND

Seats such as, for example ball seats are well known in downholeindustries and especially so in the drilling and completion industry.Commonly, ball seats are used to regulate the flow of fluids and actuatedownhole devices. Although ball seat configurations are many and areubiquitous in their use within the art, the number of stacked ball seatsthat can be employed with traditional systems is limited. Improving thenumber of ball seats that may be stacked in a borehole will be welcomedby the art.

SUMMARY

A seat apparatus includes a housing defining at least a first flow pathand at least a second flow path, a first seat disposed in the housingfor receipt of a first object operative to obstruct the first flow path,and a second seat disposed in the housing for receipt of a second objectoperative to obstruct the second flow path.

A seat apparatus includes a housing defining at least a first flow path,the axis of the first flow path coincident with a longitudinal axis ofthe housing, at least a second flow path partially defined by thehousing, a first seat disposed in the housing for receipt of a firstobject operative to obstruct the first flow path, and a second seatdisposed in the housing for receipt of a second object operative toobstruct the second flow path.

A method for facilitating a pressure based operation in a downholeenvironment comprises disposing a first object in a first seat in ahousing, the first object operative to obstruct a first flow pathpartially defined by the housing, and disposing a second object in asecond seat in the housing, the second object operative to obstruct asecond flow path partially defined by the housing.

BRIEF DESCRIPTION OF THE DRAWINGS

Referring now to the drawings wherein like elements are numbered alikein the several figures:

FIG. 1 is a perspective view of an embodiment of a ball seat;

FIG. 2 is a cut-away side view of the ball seat of FIG. 1;

FIG. 3 is a side cut-away view of a portion of an alternate embodimentof a ball seat;

FIG. 4 is a perspective view of another alternate embodiment of a ballseat;

FIG. 5 is a side cut-away view of the ball seat of FIG. 4.

DETAILED DESCRIPTION

Referring to FIG. 1, an exemplary embodiment of a ball seat 10 isillustrated. The ball seat 10 includes a housing 12 that includestubular orifices 14. The tubular orifices 14 define flow paths indicatedby the arrows 11. Seats 16 are disposed at the apertures of the orifices14. The illustrated embodiment includes concave portions 18 defined bythe housing 12. The concave portions may be, for example, conical,parabolic, or cylindrical in shape.

FIG. 2 illustrates a cut-away view of the ball seat 10. In operation,the ball seat 10 may be placed downhole in a borehole. A first object 20such as, for example, a spherical object may be introduced into theborehole and driven towards the ball seat 10 by, for example, hydraulicpressure or gravity. One of the concave portions 18 directs the firstobject 20 into engagement with a seat 16; blocking an orifice 14 andobstructing a flow path 11. A second object 22 may similarly be driventowards the ball seat 10 and directed by the concave portions 18 intothe empty seat 16; blocking the second orifice 14 and obstructing thesecond flow path 11. The obstruction of the flow paths allows anoperator to pressure up against the obstructed ball seat 10 tofacilitate a downhole pressure based operation. This may be a fracturingjob or actuation of a desired downhole device, or to otherwise effectdesired downhole operations.

Previous ball seat devices using a single orifice and seat arrangementmay be less effective when the cross sectional areas of the orifice (andthe associated diameter of the object) are less than a defined thresholdcross sectional area. The threshold diameter may be a different diameterfor different borehole systems and is associated with the likelihood ofa pressure increase upstream of the orifice due to its restricted flowarea. Orifice cross sectional areas less than the threshold crosssectional area may undesirably restrict the flow of fluid and cause theundesired and premature actuation of tools or other premature operationsuphole relative to the ball seat device. The illustrated embodimentshaving more than one orifice allow the cross sectional areas ofindividual orifices (and the associated diameter of the objects) to bereduced while avoiding the restriction of the flow of fluid since theuse of multiple orifices allows the net cross sectional area of theorifices to remain greater than the threshold cross sectional area.

FIG. 3 illustrates a side cut-away view of a portion of an alternateexemplary embodiment of a ball seat 30. The ball seat 30 is similar inoperation to the ball seat 10 (of FIGS. 1 and 2) however; the seats 16in the illustrated embodiment are disposed in different planes (A andB). In the illustrated example, the plane B is located downstream in theflow path direction (as indicated by the arrows 11) relative to theplane A. The disposition of the seats 16 in different planes may improvethe performance of the ball seat 30.

FIG. 4 illustrates another alternate embodiment of a ball seat 40. Theball seat 40 operates in a similar manner to the embodiments describedabove, and includes a plurality of seats 16 and concave portions 18. Inthe illustrated embodiment, a seat 17 and associated flow path 15 havean axis coincident to the longitudinal axis 19 of the ball seat 40. Theseats 16 and associated flow paths 14 are disposed radialy about theaxis 19 in the housing 12. FIG. 5 illustrates a side partially cut-awayview of a portion of the ball seat 40 (of FIG. 4).

The Figures described above illustrate exemplary embodiments of ballseats. Other embodiments may include any number of ball seats havingmultiple seat portions, flow paths, alignment planes, and shapes thatare operative to direct objects to engage the seats.

While one or more embodiments have been shown and described,modifications and substitutions may be made thereto without departingfrom the spirit and scope of the invention. Accordingly, it is to beunderstood that the present invention has been described by way ofillustrations and not limitation.

1. A seat apparatus comprising: a housing defining at least a first flowpath and at least a second flow path; a first seat disposed in thehousing for receipt of a first object operative to obstruct the firstflow path; and a second seat disposed in the housing for receipt of asecond object operative to obstruct the second flow path.
 2. The seatapparatus as claimed in claim 1 wherein the housing includes a firstconcave portion operative to guide the first object towards the firstseat.
 3. The seat apparatus as claimed in claim 1 wherein the housingincludes a second concave portion operative to guide the second objecttowards the second seat.
 4. The seat apparatus as claimed in claim 1wherein the first seat and the second seat are coplanar.
 5. The seatapparatus as claimed in claim 1 wherein the first seat is disposed on afirst plane and the second seat is disposed on a second plane.
 6. Theseat apparatus as claimed in claim 1 wherein the first object isspherically shaped.
 7. The seat apparatus as claimed in claim 1 whereinthe first flow path defined by the housing is tubular.
 8. The seatapparatus as claimed in claim 2 wherein the concave portion isparabolicly shaped.
 9. The seat apparatus as claimed in claim 2 whereinthe concave portion is conically shaped.
 10. A seat apparatuscomprising: a housing defining at least a first flow path, the axis ofthe first flow path coincident with a longitudinal axis of the housing;at least a second flow path partially defined by the housing; a firstseat disposed in the housing for receipt of a first object operative toobstruct the first flow path; and a second seat disposed in the housingfor receipt of a second object operative to obstruct the second flowpath.
 11. The seat apparatus as claimed in claim 10 wherein the housingincludes a first concave portion operative to guide the first objecttowards the first seat.
 12. The seat apparatus as claimed in claim 10wherein the housing includes a second concave portion operative to guidethe second object towards the second seat.
 13. The seat apparatus asclaimed in claim 10 wherein the first seat and the second seat arecoplanar.
 14. The seat apparatus as claimed in claim 10 wherein thefirst seat is disposed on a first plane and the second seat is disposedon a second plane.
 15. The seat apparatus as claimed in claim 10 whereinthe first object is spherically shaped.
 16. The seat apparatus asclaimed in claim 10 wherein the first flow path defined by the housingis tubular.
 17. The seat apparatus as claimed in claim 11 wherein theconcave portion is parabolicly shaped.
 18. The seat apparatus as claimedin claim 11 wherein the concave portion is conically shaped.
 19. Amethod for facilitating a pressure based operation in a downholeenvironment comprising: disposing a first object in a first seat in ahousing, the first object operative to engage the first seat and toobstruct a first flow path partially defined by the housing; anddisposing a second object in a second seat in the housing, the secondobject operative to engage the second seat and obstruct a second flowpath partially defined by the housing.
 20. The method of claim 19,wherein the method further comprises applying a hydraulic pressure tothe housing, the hydraulic pressure operative to actuate the downholedevice.